feat(collab): presence P1 — awareness transport + who's-here roster (collab-presence 0001)

- provider.ts: expose awareness on YjsProvider (partykit/hocuspocus surface
  their own; BroadcastChannel gets a sibling-channel relay via awareness-bc.ts)
- presence.ts: createPresence — publish local PresenceState, subscribable
  deduped peers() roster, setCursor/setSelection for P2, pagehide fast removal
- PresenceRoster.tsx + WasmTool wiring: facepile chip next to SourceChip;
  eeschema rebinds per active sheet (sheet-manager ActiveSheet now carries the
  room's provider); config presenceUser() = slug + colorForUser
- new dep y-protocols; unit tests (presence.test.ts) + e2e
  tests/web/presence-roster.spec.ts (two tabs, verified vs real partykit)
- bump pcbjam-shared: presence-wire schema (MIT)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CvqUd4QsJSGHN28aunJRTq

tests/web/presence-roster.spec.ts

@@ -0,0 +1,61 @@
+import { test, expect, type Page } from '@playwright/test';
+
+/**
+ * Presence roster e2e (collab-presence 0001): two tabs of the real React app on
+ * the SAME project file share one collab room over the default BroadcastChannel
+ * provider — each tab's PresenceRoster chip must show the OTHER user, and a tab
+ * leaving must drop off the peer's roster promptly (pagehide broadcast, not the
+ * 30s awareness timeout).
+ *
+ * Uses pl_editor (demo.kicad_wks): it is in COLLAB_TOOLS and is the smallest
+ * wasm, so the two boots stay cheap. Identity comes from the `?user=` slug
+ * (the e2e isolation hook config.ts already honors).
+ *
+ * Provider-agnostic: BC (default checkout) removes instantly via the pagehide
+ * broadcast; partykit removes when the server sees the WS close — measured
+ * ~5-8s under local wrangler dev (immediate close on real tab close; an
+ * about:blank navigation can BFCache the page and stretch this to ~15s, which
+ * is why the leave step CLOSES the tab).
+ */
+
+const SCOPE = 'default';
+const ROUTE = 'demo.kicad_wks';
+const TITLE = /demo — Drawing Sheet Editor/i;
+
+async function bootAs(page: Page, user: string): Promise<void> {
+  await page.goto(`/${SCOPE}/projects/demo/${ROUTE}?user=${user}`);
+  await expect(page.locator('#canvas')).toBeVisible({ timeout: 120000 });
+  await expect
+    .poll(() => page.title(), {
+      message: `${user}: editor never reached the expected title`,
+      timeout: 120000,
+      intervals: [1000],
+    })
+    .toMatch(TITLE);
+}
+
+test('two tabs on one file see each other in the roster; leaving removes promptly', async ({
+  page,
+  context,
+}) => {
+  test.setTimeout(360000); // two full tool boots
+
+  await bootAs(page, 'alice');
+
+  // Before anyone else joins, alice has no roster chip at all.
+  await expect(page.getByTestId('presence-roster')).toHaveCount(0);
+
+  const pageB = await context.newPage();
+  await bootAs(pageB, 'bob');
+
+  // Each side shows the other user (avatar keyed by slug), not itself.
+  await expect(page.locator('[data-presence-user="bob"]')).toBeVisible({ timeout: 30000 });
+  await expect(pageB.locator('[data-presence-user="alice"]')).toBeVisible({ timeout: 30000 });
+  await expect(page.locator('[data-presence-user="alice"]')).toHaveCount(0);
+  await expect(pageB.locator('[data-presence-user="bob"]')).toHaveCount(0);
+
+  // bob leaves (tab close → BC pagehide broadcast / partykit WS close): alice's
+  // roster must clear well inside the 30s awareness timeout.
+  await pageB.close();
+  await expect(page.getByTestId('presence-roster')).toHaveCount(0, { timeout: 20000 });
+});